Pest description and damage Sapygid wasps are tiny and black with yellow markings along the body. The first instar larvae of this wasp-like parasite is only about 0.1 the size of the bee egg, but it is able to puncture the bee egg, either parasitizing the host or causing the host egg to collapse.
Sapygid wasps will spend the night in bee holes but prefer to dwell in smaller holes. Night station traps target this behavior and are effective. They are made of hollow plastic pipes, containing insecticide inside, with small (2.5 mm diameter) holes. Sapygid wasps are attracted to the holes at night but once inside they are killed by the insecticide. White, light blue or green painted emergence traps placed in front of the bee nest are also effective at capturing sapygid wasps.
For more information:
Pitts-Singer T.L. and J.H. Cane. 2011. The alfalfa leafcutting bee, Megachile rotundata: the world's most intensively managed solitary bee. Annu. Rev. Entomol 56: 221-237.